Issue 65: Update default hostname in cucumber profile from google.com to scanme.nmap.org

Updated the hostname in the cucumber profile and adjusted the attack files and rake tests accordingly

HOWTO wiki article is complete as well!
https://github.com/boldersecurity/gauntlt/wiki/Using-Cucumber-Profiles-and-Environment-Variables-with-Gauntlt

If all looks well and wiki article integrated, I'll post to the gauntlt mailing list.